Total isomerization process

Claim 1

A process for the virtually complete isomerization of normal paraffin hydrocarbons contained in a feed stream consisting essentially of mixed normal and non-normal hydrocarbons comprising (a) passing a combined reactor feed of said feed stream and a desorption effluent, as hereinafter delineated, through an isomerization reactor containing an isomerization catalyst and including hydrogen in said reactor feed to convert at least a portion of the normal hydrocarbons in said reactor feed to non-normal hydrocarbons; (b) passing the reactor effluent from the reactor to an adsorption section and adsorbing the normal hydrocarbons remaining in the reactor effluent in a molecular sieve zeolite adsorber bed and passing the non-normal hydrocarbons out of the adsorption section as adsorber effluent containing an isomerate product; (c) desorbing the adsorber bed with an essentially constant hydrogen purge gas thereby producing a variable desorption vapor effluent comprised of a constant flow of hydrogen purge gas which contains a varying concentration of desorbed normal hydrocarbons in the range of 20 to 30 mole percent at the beginning of the desorption step to less than 5 mole percent at the end of such step; and (d) controllably varying the fresh feed stream flow rate and blending such fresh feed stream with the desorption effluent produced in step (c) to provide a constant flow of combined reactor feed in step (a).